package Number_of_tourists;



public class Number implements Changeable{
    int pnum,in,out;
    @Override
    public void add() {
        pnum += UNITS * in;
    }

    @Override
    public void reducible() {
        pnum -= UNITS*out;
    }

    public static void main(String[] args) {
        Number n = new Number();
        n.in = 7;
        n.out = 4;
        n.add();
        n.reducible();
        System.out.println("景区里还有"+n.pnum+"人");
    }
}
